Method of and apparatus for the reception of radiosignals



July 21, 1925. 1,546,639

'0. L. FARRAND METHOD OF AND'APPARATUS FOR THE RECEPTION OF RADIOSIGNALS7 Filed May 14, -1919 INVENTOR Claz'r L. J b/rand dmw ATTORNEY PatentedJuly 21, W2.

CLAIR L. FARRAND, OF ELIZABETH, NEW JERSEY, ASSIGNOR OF ONE-THIRD T'OCOR- NJELIUS D. EHRET, OF MOUNT AIR/Y, PHILADELPHIA, PENNSYLVANIA.

METHOD OF AND APPARATUS FOR Application filed May 14,

To all whom, it may concern:

Be it known that I, CLAIR L. FARRAND, a citizen of the United States,residing at the city of Elizabeth, in the county of Union and State ofNew Jersey, have invented a Method of and Apparatus for the Reception ofRadiosignals, "of which the following is a specification.

The object of this invention is to provide a means for the reception ofradio tele graphic signals, particularly signals of undamped waves.

My invention depends upon the discoveries first, that the rate ofrectification of high frequency currents can be periodically regulatedso as to produce audible tones when the frequencies used are above therange of audibility; second, that the direct current produced by arectifier of high frequency currents can be periodically regulated inamplitude so as to produce audible tones when the frequencies used areabove the range of audibility.

The .following is a description of the method of and apparatus forattaining the above results, and will best be understood by referring tothe accon'ipanying drawings, wherein the same numerals refer tocorresponding parts in all figures. Fig. 1 shows diagrammatically themethod of practicing my invention involving a means of extracting energyfrom the rectified wave impulses; Fig. 1 shows diagrammatically the samemeans as in Fig. 1, excepting that a transformer is used between theenergy extracting circuit and the detector circuit; Fig. 2 showsdiagran'miatically the method involving the periodic regulation of therate of rectification of the high frequency wave impulses; Fig. 3 showsdiagrammatically the method utilizing a reactance for periodicallyregulating the amplitude of the rectified high frequency current.

Referring to Fig. 1, the numeral 1 is the antenna, 2 is the primaryinductance, 3 is the earth, 4 is the secondary inductance, 5 is thesecondary condenser, comprisingthe usual two circuits of the receiver, 6is the cathode, and 7 is the anode of a high frequency rectifier hereshown as a two elec trode vacuum valve, although any desired form ofrectifier may be used; '8 is the telephone receiver, 9 is the filament,10 is the grid, and 11. is the plate of a three electrode THE RECEPTION0F BAIDIOSIGNALS.

1919. Serial No. 296,960.

vacuum valve,- 12 is the filament battery, 13 is a source of alternatingvoltage which may be an alternator, buzzergencrator, valve-generator, orother suitable source; 14 is the filament battery for the two electroderectifying vacuum valve. In operation the electromotive force of thehigh frequency signal is applied to the rectifying valve and produces adirect currentin the telephone 8, across which is shunted theplate-filament circuit of the three electrode valve. The resistance ofthis plate-filament circuit is relatively high when the grid is at anegative potential with respect to the filament. When an alternatingpotential is applied to the grid with respect to the filament theresistance of the plate-filament circuit periodically varies,periodically extracting current from the telephone, and producing, ineffect, an alternating current in the telephone. It will be understoodthat sound is produced by the telephone only when the signal is appliedto the circuit. It is sometimes advisable to connect a transformerbetween the telephone and the platefilalnent circuit of the regulatingvalve in order to compensate for the difference of impedance which mayexist, as shown by 27 in Fig. 1*.

Referring to Fig. 2, the numeral is a grid placed between the filament 6and the plate 7 of the rectifier, comprising a three electrode valve,the hot and cold elements of which are used to rectify the highfrequency signal current, and the third influencing member or grid 15 isused to control the rate of rectification. The operation is as follows:The uni-directional current produced in the telephone by therectification of high frequency signal current is of constant amplitudewhen the grid15 is at a constant potential with respect to the filament.If alternating potential from the source 13 is applied, periodicallyvarying the potential of the grid, the rate of rectification isperiodically varied, periodically changing the amplitude oftheuni-directional current in the telephone, producing an audible signal.

The note produced in the telephone corresponds to the frequency of thesource 13, when the frequency of that source is in the range ofaudibility. If the frequency of the source 13 is above the range ofaudibility and approaches the frequency of the signal waves in value, aperiodic rectification occurs, changing the amplitude of theunidirectional rectified Waves at a rate corresponding to the differencebetween the frequency of rectification and the frequency of the signalwaves, and producing an audible signal corresponding in frequency tosaid difference.

Referring to Fig. 3, the numeral 16 is an inductance in series with thetelephone 8, andso disposed on a common core 17 with respect to thewindings 18 that the potential produced in winding 16 by windings 18 areequal and opposite. Alternating current from the source 13 is applied towindings 18, periodically varying the permeability of the core 17 andthe inductance of winding 16, but not inducing potential therein. Therectified high frequency current will periodically correspond inamplitude, producing in effect an alternating current in the telephone,and consequently an audible signal. Other methods may be used toperiodically vary the value of the inductance 16, such as passing theteeth of a sectored metallic disc periodically through the magneticfield produced by said inductance.

Other methods of attaining the same results are objectionable in thatthey involve the use of motors which'cause disturbances in the receivercircuits or depend upon a difference of frequency, as in the case of.the autodyne, which involves detuning and a resultant low power factor.

In the present invention the same result is accomplished withoutnecessity for use of the objectionable motor, and the signal can bereceived with the circuits adjusted to substantially unity power factorwith reference to the frequency of the signal wave.

It is not intended to limit the invention to the figures and apparatusas described, as the invention is susceptible of various modivficationscapable of regulating the amplitude of the rectified high frequencyimpulses by the periodic extraction of energy with resistance or by theperiodic regulation of cur-,,

rent flow with inductive or capacitive reactance. Figs. 1, 1, and 3indicate the possibilities of these applications, or as in Fig. 2,methods of periodically regulating the rate of rectification involvingelectrostatic or electromagnetic fields of, first, high fre quency or,second, low frequency.

Impedance variation of the character herein described at frequency-aboveaudibility or at radio frequency is claimed in my application Serial No.330,488, filed October I-Iaving thus claim:

1. The method of receiving and translating into a signal radio frequencysignal-representing energy, which comprises receivin described myinvention, I

the signal-representing energy, and rectifying the current thereof in acircuit whose impedance is always finite, independently varying theimpedance of said circuit at predetermined frequency by variations of anelectrostatic field, and translating into a signal the rectified currentas modified by said impedance variation.

2. The method of receiving and translating into a signal radio frequencysignal-representing energy, which comprises receiving thesignal-representing energy, and rectifying the current thereof in acircuit, independently generating an electro-motiveforce varying inamplitude at predetermined frequency, producing variations of impedanceof said circuit by varying an electrostatic field produced by saidelectro-motiveforce, and translating into a signal the rectified currentas modified by said impedance Variation.

3. The method of receiving and translating into a signal radio frequencysignal-representing energy, which comprises receiving thesignal-representing energy, and rectifying the current thereof in acircuit whose impedance is always finite, independently generating anelectro-motive-force varying in amplitude at predetermined frequencydifferent from the frequency of said current, producing variations ofimpedance of said circuit by varying an electrostatic field produced bysaid electro-motive-force, and translating into a signal the rectifiedcurrent as modified by said impedance variation. v

4. The method of receiving and translating into a signal radio frequencysignalrepresenting energy, which comprises receiving thesignal-representing energy, impressing the same upon the anode-cathodecircuit of a thermionic impedance, independently varying the impedanceof said circuit at predetermined frequency by varying an electrostaticfield, and translating into a signal the current in said circuit asmodified by said impedance variations.

5. The method of receiving and translating into a signal radio frequencysignal-representing energy, which comprises receiving thesignal-representing energy, impressing the same upon the anode-cathodecircuit of a thermionic impedance, independently varying the impedanceof said circuit by varying an electrostatic field at predeterminedfrequency different from the frequency of the current in said circuit,and" translating into a signal the current in said circuit as modifiedby said impedance variations.

6. The method of receiving and translating into a si a1 radio frequencyenergy, which comprises impressing the received energy upon a circuitwith which is operatively related a thermionic device comprising ananode, cathode and control electrode,

periodically varying the potential of said control electrodeindependently of the received energy, and translating the resultantcurrent into a signal.

7. The method of receiving and translating into a signal radio frequencyenergy, Which comprises impressing the received energy upon a circuitWith Which is operatively related a thermionic device comprising ananode, cathode and control electrode, periodically varying the potentialof said control electrode at audio frequency inde pendently of thereceived energy, and translating the resultant current into a signal.

8. The method of receiving and translating into a signal radio frequencysignalrepresenting energy, which comprises receiving thesignal-representing energy, impressing the same upon the anode-cathodecircuit of a thermionic impedance, varying the discharge between saidanode and cathode by an electrostatic field fluctuating at apredetermined frequency, causing said field fluctuation by anindependent source of fluctuating current, and translating into a signalthe current in said circuit as modified by said variation ofsaid'discharge.

9. The method of receiving and translating into a signal radio frequencysignalrepresenting energy, Which comprises receiving thesignal-representing energy, impressing the same upon the anode-cathodecircuit of a thermionic impedance, varying the discharge between saidanode and cathode by an electrostatic field fluctuating at apredetermined frequency different from the frequency of the current insaid circuit, causing said field fluctuation by an independent source offluctuating current, and translating into a signal the current in saidcircuit as modified by said variation of said discharge.

10. Receiving apparatus for translating radio frequency currentcomprising a thermionic device comprising an anode and a cathode, meansfor impressing the received current upon the anode-cathode circuit, atranslating instrument subjected to the rectified current, andelectrostatic means for independently varying the impedance of saidcircuit for varying the amplitude of the rectified current traversingsaid translating instrument.

11. Receiving apparatus for translating radio frequency currentcomprising a thermionic device comprising an anode, grid and cathode,means for impressing the received current upon the anode-cathodecircuit, a translating instrument subjected to the rectified current,and means for varying independently of control by said circuit thepotential of said grid at a different frequency. i

12. Receiving apparatus for translating radio frequency currentcomprising a thermionic device comprising an anode, grid and cathode,means for impressing the received current upon the anode-cathodecircuit, a translating instrument subjected to the rectified current,and a source of alternating current of different frequency for varyingindependently of control by said circuit the potential of said grid.

13. Receiving apparatus for translating radio frequency currentcomprising a circuit, a thermionic device comprising an anode andcathode in said circuit, said circuit being normally Without current,means for impressing the received current upon said anode-cathodecircuit, a translating instrument subjected to the modified receivedcurrent in said circuit, and means producing an electrostatic field forindependently varying the impedance of said circuit for varying theamplitude of said current.

14. Receiving apparatus for translating radio frequency currentcomprising a circuit, a thermionic device comprising an anode, cathodeand electrostatic field-producing means for varying the discharge between said anode and cathode, said anode and cathode being disposed insaid circuit and said field-producing means being ex ternal to saidcircuit, means for independently varying said field for varying theamplitude of the modified current in said circuit, and a translatinginstrument subjected to said modified current of varying amplitude.

15. Receiving apparatus for translating radio frequency currentcomprising a circuit, athermionic device comprising an anode, cathodeand grid, said anode and cathode being disposed in said circuit and saidgrid being independent of control by said circuit, said circuit bcirgnormally Without current, and means for independently Varying thepotential of said grid for varying the amplitude of the modified currentin said circuit, and a translating instrument subjected to said modifiedcurrent of varying amplitude.

16. Receiving apparatus for translating radio frequency currentcomprising a circuit, a thermionic device comprising an anode, cathodeand grid, said anode and cathode being disposed in said circuit and saidgrid being independent of control by said circuit, said circuit beingnormally Without current, means for independently varying the potentialof said grid at a uniform frequency differing from the frequency of thecurrent in said circuit, and a translating instrument subject to themodified current in said circuit.

1 17. Receiving apparatus for translating radio frequency Wavescomprising a thermionic device comprising an anode, cathode and acontrol electrode, means for controlling the anode-cathode circuit bysaid waves, and means for varying independently of control by saidcircuit the potential of said control electrode.

18. Receiving apparatus for translating radio frequency waves comprisinga thermionic device comprising an anode, cathode and a controlelectrode, means for controlling the anode-cathode circuit by saidwaves, and means for varying independently of control by said circuitthe potential of said control electrode at a frequency independent ofthe frequency of said Waves.

19. Receiving apparatus for translating radio frequency waves comprisinga thermionic device comprising an anode, cathode and a controlelectrode, means for impressing said Waves upon the anode-cathodecircuit, and means for varying independently of control by said circuitthe potential of said control electrode.

20. Receiving apparatus for translating radio frequency Waves comprisinga thermionic device comprising an anode, cathode and a controlelectrode, means for impressing said Waves upon the anode-cathodecircuit, and means for varying independently of control by said circuitthe potential of said control electrode at a frequency independent ofthe frequency of said Waves.

21. In the art of receiving and rendering intelligible radio frequencywaves, the method which comprises effecting rectification of the wavesby asymmetrically conducting thermionic impedance,. and independentlyvarying the rate of rectification by an electrostatic field varying at afrequency independent of the frequency of said waves. I

22. Receiving apparatus for translating radio frequency waves comprisinga thermionic device comprising an anode, cathode and electrostaticfield-producing means for varying the discharge between said anode andcathode, a circuit including said anode and cathode, means for causingin said circuit current fluctuations of a frequency corresponding withthe frequency of the received energy, and means so-acting with saidfield-producing means for independently periodically varying theimpedance of said anode cathode circuit at a predetermined frequencydiffering from the frequency of said current fluctuations.

v 23. The method of receiving and trans lating into a signal radiofrequency signal representing energy, which comprises re ceiving thesignal representing energy,

rectifying the current thereof in a circuit Whose impedance is alwaysfinite, independently generating an electromotive force varying inamplitude at a predetermined frequency, utilizing the elcctromotiveforce thus generated to produce an electrostatic field which is entirelyindependent of any field produced by signal representing energy,producing by means of this field variations in the impedance of saidcircuit and translating into a signal the rectified current as modifiedby said impedance variation.

24. Receiving apparatus for translating radio frequency currentcomprising a circuit, means for impressing signal representing radiofrequency currents upon said circuit, a thermionic device comprising ananode and a cathode included in said circuit, electrostatic fieldproducing means which are external to said circuit, means for vary ingsaid field exclusively by a local source of currents, and independentlyof any signal representing currents, and thereby varying the amplitudeof the current in said circuit, and a translating instrument subjectedto said current of varying amplitude.

25. Receiving apparatus for translating radio frequency Waves comprisinga circuit upon which the energy of the received radio frequency waves isimpressed, a thermionic rectifier comprising an electron-emittingcathode and an anode connected in said circuit, a signal-translatinginstrument af fected by the rectified current, a control electrode, andmeans for varying at audio frequency and independently of the receivedenergy the potential of said control electrode for varying the impedanceof said thermionic device.

26. Receiving apparatus for translating radio frequency waves comprisinga circuit upon which the energy of the received radio frequency waves isimpressed, said circuit being substantially devoid 'of electrical energyother than said received energy, a thermionic rectifier comprising anelectronemitting cathode and an anode connected in said circuit, asignal-translating instrument affected by the rectified current, a control electrode, and means for varying at audio frequency andindependently of the received energy the potential of said controlelectrode for varying the impedance of said thermionic device.

CLAIR FARRAND.

